In general, a metallic bottle can (referred to as “a bottle can” hereinafter) is formed by performing processing such as drawing or ironing a metallic sheet made of aluminum or an aluminum alloy in multiple steps, and is widely used as a container for drinks.
An apparatus for producing such a bottle can is equipped with a work holding part which has a die-ring for holding a closed-end cylindrical body shaped from a metallic sheet, and a tool holding part for holding a processing tool for performing a shaping processing on the closed-end cylindrical body, in which the die-ring is circularly arranged and held onto the surface of a disc at one side, whereas the processing tool is circularly arranged and held onto surface of a disc at another side so as to be opposed to each die-ring.
The closed-end cylindrical body is held by the die-ring so as to direct an opening part thereof toward the tool holding part, while aligning the center line thereof with that of the work holding part and tool holding part.
The tool holding part is equipped with various tools (machine tools), as processing tools, for processing corresponding to each processing step, such as plural drawing dies for shaping the opening part of the closed-end cylindrical body into a tapered part or a metal cap by nosing it (neck-in processing), a tool for forming a screw in a metal cap, and a tool for forming a curling part at the open end, etc., and these tools are arranged in order of processing.
It should be noted that as steps of processing which are performed on a closed-end cylindrical body, a neck-in processing to shorten the diameter of the opening part by plural steps, a trimming processing to trim the open-end of the metal cap shaped by the neck-in processing thereby adjusting the height of the closed-end cylindrical body, a screw-shaping processing to shape the metal cap into a screw, a curling part forming processing to curl the open-end part of the metal cap outward in the radial direction, a slot processing to press the outer surface of the curling part inwardly in the radial direction and collapse the outer surface, etc. are exemplary. By using processing tools corresponding to each of these processings, the closed-end cylindrical body is shaped, thereby producing a bottle can.
Moreover, the work holding part and the tool holding part are held so that they can rotate relatively to each other and move in the direction of the center line relatively to each other, and these holding parts rotate relatively to each other, so that each tool can perform processing corresponding to each step on a closed-end cylindrical body when the work holding part and the tool holding part come close to each other, and that the processing tool for the subsequent step can face each closed-end cylindrical body when these holding parts move away from each other. In this way, the action of performing processing when both holding parts come close and rotating when both holding parts move away is repeated, thereby shaping a shoulder part, a metal cap part, a screw shape, etc. successively onto a closed-end cylindrical body to impart the shape of a bottle can.
The bottle can thus shaped is filled with a filling, and then sealed with a cap which is disposed on the metal cap part. The cap is applied by deforming a cap member which is made of aluminum or aluminum alloy shaped into a cup, so as to fit to the screw shape which is formed on the metal cap part. In general, this cap member is applied by rotating disc rollers, while pressing these rollers to the perimeter of the cap member (capping step).
First, the rollers abut an upper part (top face side) of the cap member and start to rotate, and then come into contact with the upper end of the screw thread of the metal cap part while rotating on the perimeter of the cap member, at this time the rollers are introduced by the screw thread shape to come into contact with the thread groove from the upper end of the screw, and rotate up to the lower end of the thread groove. Thus, a screw shape is shaped onto the cap member, thereby applying the cap to the metal cap part of the bottle can.